Carbapenems

Summary

Carbapenems are a class of antibiotics used to treat a variety of bacterial infections. Like penicillins, these drugs are beta-lactam antibiotics; they are D-Ala-D-Ala analogs that bind to and block the bacterial transpeptidase, thereby preventing the cross-linking of the bacterial cell wall. Carbapenems are also resistant to penicillinase, a bacterial enzyme that can deactivate penicillins by cleaving the beta-lactam ring. Because of this, carbapenems can be used to treat bacterial infections when other beta-lactam antibiotics have failed. However, carbapenems also have major side effects. Patients can experience seizures due to the neurotoxic effects of these drugs. Other side effects of the carbapenems include rash and GI upset.

Key Points

• Carbapenems
  • Drug Names (-penem endings)
    • Imipenem
    • Meropenem
    • Ertapenem
    • Doripenem
  • Mechanism
    • Beta-lactam antibiotics
      • Bind to penicillin-binding proteins (PBPs) to prevent peptidoglycan cross-linking in bacterial cell wall
    • Imipenem administered with cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules
      • Meropenem is stable against renal dehydropeptidase I
  • Clinical Use
    • Broad-spectrum coverage
      • Gram-positive cocci
      • Gram-negative rods
      • Anaerobes
    • Used for life-threatening infections after other drugs have failed
  • Adverse Effects
    • Seizures
      • Due to CNS toxicity
      • Meropenem has a lower risk of seizures
    • GI distress
    • Rash
  • Resistance
    • Not susceptible to beta-lactamase (penicillinase)
    • Carbapenemases (cleave carbapenems)
      • Produced by K. pneumoniae, E. coli, and E. aerogenes